I just wrote another message in which I mention rarely using the components from list-context localtime(), except to feed into strftime(). This is one of those rare situations which call for using the components. In scalar context, localtime() gives you a fully formatted date-time string, but in list context it returns:

my ( $seconds,            $minutes,     $hours, 
     $day_of_month,       $month_idx,   $years_since_1900,
     $day_of_week_number, $day_of_year, $id_dst 
   ) = localtime($now);

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So rather than generating a date string "Sat Aug 21 22:00:53 2010" and then parsing it with a regex ( not even substr()! .. shocking! ), why not use the day of the week component .... 0 == Sunday through to 6 == Saturday. 
$now -= 43200 while (localtime($now))[6]; # count back half days till 
+Sunday

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--
TTTATCGGTCGTTATATAGATGTTTGCA

In reply to Re^2: Is there an easy way to get the start date of the current week? by TomDLux
in thread Is there an easy way to get the start date of the current week? by ramjamman

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